Preserving memory resources by limiting time-date information for a subset of properties

ABSTRACT

Example embodiments provide for preserving memory resources by selecting property values to be assigned time-date information used in resolving conflicts between sync values. The property values may be selected based on the available resources of a remote device, e.g., when the time-date information is to be stored in a field of limited space. Further, the property values may be selected based on historical information, such as the most recently or frequently modified values. Other example embodiments also provide for storing an upper and/or lower boundary of time-date information for the remaining property values not selected. For example, the most recently modified property time-date value may be used for the upper boundary and the oldest modified time-date value may be used for the lower boundary.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of commonly-assigned U.S.patent application Ser. No. 10/878,095, filed on Jun. 28, 2004, alsoentitled “Preserving Memory Resources by Limiting Time-Date Informationfor a Subset of Properties”, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention generally relates to synchronizing data within adistributed computing system. More particularly, the present inventionprovides for preserving memory resources by limiting time-dateinformation for a subset of properties, the time-date information usedfor resolving conflicts between sync values.

2. Background and Related Art

Laptop, handheld, and other portable computers or computing devices haveincreased in popularity as the devices become smaller in size and lessexpensive. Additionally, improved operating speed and processing powerof portable computers has increased their popularity. Many portablecomputers are capable of storing multiple application programs, such asaddress books, games, calculators, and the like. The applicationprograms can be permanently installed in the portable computer duringmanufacture (e.g., on Read-Only Memory (ROM)). Alternatively, one ormore application programs may be installed by the user after purchasingthe portable computer.

With the increased popularity and computing power of such devices,people are beginning to store data and applications using more than justa single computing device. Many people, for example, often use laptopcomputers in addition to their regular desktop computer. Other devicessuch as cellular telephones, Personal Digital Assistance (PDAs),Internet services, and the like are also used for storing data andapplications.

Each of these computing devices may be part of a distributed computingsystem wherein related information can be correlated and stored onmultiple such devices. For example, a user may have a digital addressbook stored on their desktop work computer, on their PDA, on their cellphone, on an Internet service, etc. Accordingly, while at work, it maybe convenient for the user to access contact information, which mayinclude phone numbers and other general contact information. While awayfrom work, however, the user may be able to use the address book in amobile form such as a personal digital assistance (PDA) or other mobileinformation storage system. Ideally, the contact information of the PDAshould match the contact information at the desktop work computer.

When the same or related information is stored in two places, it ispossible for the data to change in one location and not in the other.This problem may be overcome through synchronization, which is anautomated process that attempts to ensure that each device within thedistributed system has the most current information or data.Synchronization, however, has its own set of problems. For example, whensynchronization is initialized between the two devices, current systemsdetect changed property values by comparing corresponding propertyvalues from each device. Such comparison, however, gives no indicationas to which device made the change. As such, when a property change hasoccurred on either device, a conflict occurs and a conflict resolutionprocess must be performed.

Other systems mark a changed property with a tag indicating that achange has occurred, e.g., “change,” “delete,” “add,” or other tag, asappropriate. In such systems, however, when two devices start syncing, alocal device can create these markers in memory after comparing the datafor what needs to be applied. Further, because the tags are only trackedin memory, these tags are not stored in a remote database for use duringsynchronization with other devices. In other words, conflicts must firstbe reconciled and then the properties can be marked and tracked in localmemory only.

Typically, conflicts can be resolved through comparing metadataassociated with the property values that give, e.g., time-dateinformation. The latest time-date information is considered the mostup-to-date information and the properties can be updated accordingly.Resolving a conflict by comparing time-date information becomesparticularly problematic when the data to be synchronized does notinclude time-date information, which is referred to as low fidelitydata. For example, many smaller computing devices have limited physicalresources and are incapable of maintaining time-date information forproperties of a data structure item. As such, when a computer syncs datain from such low fidelity device, it doesn't know when the useroriginally set that property. This prevents the computer from syncing ina property from another computing device and confidently using“last-writer-wins” resolution logic to pick the most up-to-dateproperty. Further, even if no conflict existed, there is typically noway to sync the property change to the receiving device without aconflict resolution process.

BRIEF SUMMARY OF THE INVENTION

The above-identified deficiencies and drawbacks of currentsynchronization systems are overcome by the present invention. Forexample, exemplary embodiments provide for preserving memory resourcesby selecting property values to be assigned time-date information usedin resolving conflicts between sync values.

Example embodiments provide for receiving a plurality of property valuesfrom a remote device. A limited set of property values from among theplurality of property values received are selected based on theavailable resources of the remote device. Further, a set of time-dateinformation from a plurality of time-date information corresponding tothe plurality of property values is identified. Each of the propertyvalues in the limited set corresponding to a different portion of theset of time-date information and indicating when each of the propertyvalues within the limited set where last modified. The differentportions of time-date information are then stored in a remote databaseof the remote device.

Other example embodiments provide that the selection of the limited setof property values may also be based historical information associatedwith the modification of the plurality of property values. For example,the historical information may be the frequency for which each of theplurality of property values are modified, and the most frequentlymodified property values may then be selected. Alternatively, or inconjunction, the historical information may be time-date information forthe plurality of property values, and the most recently modifiedproperty values may then be selected.

Still other example embodiments provide for identifying a portion oftime-date information from the above-identified plurality of time-dateinformation for remaining property values not within the limited set ofproperty values. The portion of time-date information corresponding towhen one or more of the remaining property values where modified by auser. The identified portion of time-date information may then be storedin one location in the remote database such that the identified portionof time-date information corresponds to all of the one or more remainingproperty values.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by the practice of the invention. Thefeatures and advantages of the invention may be realized and obtained bymeans of the instruments and combinations particularly pointed out inthe appended claims. These and other features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the invention can be obtained, a moreparticular description of the invention briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only typical embodiments of the invention and are not thereforeto be considered to be limiting of its scope, the invention will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

FIG. 1A illustrates a distributed system with high fidelity and lowfidelity devices in which the present invention may be implemented;

FIG. 1B illustrates the detection of a conflict between two deviceswithin the distributed system in accordance with example embodiments ofthe present invention;

FIG. 2 illustrates updating and use of time-date information in adistributed system with a low fidelity device in accordance with exampleembodiments of the present invention;

FIG. 3 illustrates an example standard format of time-date informationwithin a field in accordance with example embodiments of the presentinvention;

FIG. 4 illustrates a flow chart of a method of associating time-dateinformation with a property value in a database without a correspondingtime-date field in accordance with example embodiments;

FIG. 5 illustrates a flow chart of a method of receiving and storingtime-date information with a property value in a database without acorresponding time-date field in accordance with example embodiments;

FIG. 6 illustrates a flow chart of a method resolving data conflictsbetween devices in a distributed computing system using time-dateinformation received from a database without a corresponding time-datefield in accordance with example embodiments;

FIG. 7 illustrates a flow chart of a method of determining when a valuefor a property on a remote has changed since a last synchronization ofthe property in accordance with example embodiments;

FIG. 8 illustrates a flow chart of a method of selecting a limited setof property values from among a plurality of property values that are tobe assigned time-date information in accordance with exampleembodiments; and

FIG. 9 illustrates an example system that provides a suitable operatingenvironment for the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention extends to methods, systems and computer programproducts for storing and maintaining time-date information for a devicethat stores properties in a database without a corresponding time-datefield. Further, the present invention provides for identifying when datahas changed on a remote device. The present invention also provides forselecting a limited set of property values to assign time-dateinformation for preserving restricted or limited memory resources. Theembodiments of the present invention may comprise a special purpose orgeneral-purpose computer including various computer hardware, asdiscussed in greater detail below.

Generally, the present invention provides for a distributed computingsystem that is capable of associating time-date information with aproperty value in the database. The distributed computing system has adevice that stores properties in a database without correspondingtime-date fields, and thus is considered a low fidelity or legacydevice. Example embodiments provide that time-date informationcorresponding to remote property values can be identified and formattedin a standard format parsable by one or more devices in the distributedcomputing system. The formatted time-date information is sent to theremote database for storage in a field associated with the remoteproperty values. The formatted time-date information can thensubsequently be used in resolving conflicts between property values.

Other example embodiments provide for determining when a value for aproperty on a remote device has changed since the last synchronizationof the property between the remote device and a local machine. Moreover,other example embodiments provide for selecting a limited set ofproperty values from among a plurality of property values based onavailable resources of the remote device.

Reference will now be made to the figures wherein like structures willbe provided with like or similar reference designations. It isunderstood that the drawings are examples of schematic representationsof embodiments of the invention, and are not meant to limit or otherwisenarrow the scope of the present invention.

FIG. 1A illustrates several nodes within a distributed computing network100 to illustrate the connections and how each node syncs with othernodes within the system. For example, as shown in the distributedcomputing system 100 work computer 105 can sync with several variousdevices such as email server 110, PDA 115, mobile phone 120, and instantmessage server 125. The purpose for synchronizing data within such adistributed computing system 100 is to ensure that the most up-to-dateinformation is provided on all devices used by one or more users.

Data needing to be synchronized may be, e.g., contact informationwherein each item would correspond to information about an individualperson, company, corporation, or any other similar contact. An exampleof the properties associated with each contact item may be first name,middle name, last name, company name, address, phone number, emailaddress, website information, etc. As one would recognize, however, thelocal data may be information other than contact information. Forexample, the local data could be a calendar and/or schedulinginformation, a file, an application or any other such informationneeding to be synced between two devices. Accordingly, reference tocontact information is used for illustrative purposes only and is notmeant to limit or otherwise narrow the scope of the present inventionexcept where explicitly claimed.

Similar to work computer 105, home laptop 130 may be able to be syncedbetween instant message server 125, mobile phone 120, PDA 115, and emailserver 110. The distributed computing system 100 may be made up of lowfidelity (e.g., a device whose database is not capable of storingtime-date information for properties) and high fidelity devices. This isimportant to consider since ideally every database would have time-dateinformation for each property in an item to indicate the last time theuser modified the property. If that was the case, then the sync adapterscould use a “last-writer-wins” rule to let the last time-dateinformation pick the winner. This would solve some looping problems andresult in the best property winning each conflict (provided the clocksused within the distributed computing system 100 are synchronized aswell). Because many distributed computing systems 100 are made up of atleast some low fidelity or legacy clients with limited memory resourcesfor storing such time-date information, and because it is desirable tosupport such legacy clients, there needs to be other ways to resolveconflicts between devices while avoiding potentially infinite syncloops.

FIG. 1B illustrates a portion of the distributed computing network 100with remote devices 116 (such as mobile phone 120 or PDA 115) and alocal machine 132 (such as home laptop 130 or work computer 105). Asshown, remote device 116 changed a property value from A to B at somepoint after the last synchronization between remote device 116 and localmachine 132. Similarly, local machine 132 changed the same propertyvalue from A to C subsequent to the last synchronization between the twodevices 116, 132. As such, remote device 116 has a needs sync arrow 135showing that the value of B for the property should be synced down tolocal machine 132. Similarly, local machine 132 has a needs sync uparrow 140 indicating that the value of C should be synced up to remotedevice 115. Because both devices 116, 132 have needs sync arrows to syncproperty values down and up, respectively, a conflict can result.

As previously mentioned, typically conflicts like the one identified inFIG. 1B can be resolved through the comparison of time-date informationassociated with the property values. Resolving a conflict by comparingtime-date information, however, becomes particularly problematic whenthe data to be synced does not include time-date information, as in thecase of low fidelity devices. This prevents the computer from syncing ina property from another computing device and confidently using“last-writer-wins” resolution logic to pick most up-to-date property.Further, another related problem associated with low fidelity devices isthere is no way to identify when a property has changed. Accordingly,even if time-date information can be associated with the low fidelitydata, such information or time-date information is potentiallyunreliable based on the fact that the properties may have been changedat the low fidelity device.

The above-identified deficiencies and drawbacks of current distributedcomputing networks are overcome through exemplary embodiments of thepresent invention. For example, the present invention provides forassociating time-date information with property values in a database,where a device stores properties without a corresponding time-date field(i.e., a low fidelity device). Further, the present invention providesfor determining when a value for a property on a remote device haschanged since the last synchronization of the property, even if theremote device is a low fidelity device.

FIG. 2 illustrates a distributed computing network 200 with a systemcapable of creating, using, and updating time-date information for a lowfidelity device in accordance with example embodiments of the presentinvention. Distributed computing system 200 includes two high fidelitymachines, local machine 210 and remote machine 220. Also included withinthe distributing computing system 200 is a low fidelity device, i.e.,remote device 205. Remote device 205 is low fidelity in that thedatabase associated with remote device 205 is not capable of storingtime-date information with each property. In other words, remote device205 stores properties in its database without a corresponding time-datefield.

Although remote device 205 does not have time-date fields for propertiesin its database, example embodiments provide for associating thetime-date information with the property values in remote device 205 andallowing remote device 205 to store the time-date information in astandard format and within a field that is unused. For instance, localmachine 210 can identify time-date information corresponding to remoteproperty values in remote devices 205 database. The identified time-dateinformation may then be formatted in a standard format parsable byseveral devices within the distributed computing system 200. Thestandard format may be, e.g., a Uniform Resource Identifier (URI). Forinstance, URI may be in the form of a Sync Uniform Resource Locator(URL) that identifies the property and includes the identified time-dateinformation associated with each property. As will be described ingreater detail below with regard to FIG. 3, this Sync URL format isdesirable because it is readily identifiable and parsable by manydevices, thus ideal as a standard format.

Local machine 210 can send to remote device 205 the formatted time-dateinformation, which will be stored in a field associated with the remoteproperty values. For example, as shown in FIG. 2, local machine 210sends item 1 (215) with Time-Date (T/D) information and updatedproperties when syncing with remote device 205. Remote device 205 thenstores item 1 (215) that includes the time-date information. Theformatted time-date information is stored in an unused property filed onthe remote device 205. For example, remote device 205 can store theformatted time-date information in a normal property, a hidden property,a private expanded property or even appended it to the end of a notesfield. It should be noted that although other information may be storedin a property field (e.g., text in a notes field), the present inventionrefers to such fields as unused because the field is not reserved forstoring time-date information. Accordingly, the use of term “unused”property field should be interpreted broadly to encompass any propertyfield not reserved for storing time-date information.

Example embodiments provide that the formatted time-date information canbe used for several different purposes, such as resolving conflicts, oridentifying when a property has changed. For instance, a sync isinitiated between remote device 205 and remote machine 220. Accordingly,item 1 (215) can be sent down to remote machine 220 with the propertiesand the formatted time-date information. Because the formatting of thetime-date information is in a standard parsable format, remote machine220 can parse the remote time-date information and identify remote timeand date information associated with each property. This remote time anddate information can then be compared with the remote machine's 220'stime-date information in resolving any conflicts between propertyvalues.

Other example embodiments provide for detecting when a property haschanged at the remote device 205. For example, the formatted time-dateinformation within item 1 (215) may include a representation of theproperty value last synced with local machine 210 within each segment ofthe time-date information. The representation may be, e.g., in the formof a hash, which would be a hash of the last synchronized property valuethat was associated with the time-date information. When remote machine220 receives item 1 (215) for syncing, the received properties withinitem 1 (215) can also be hashed using the same standard hash functionused to hash the last synced property value. Standard hash functionsthat may be used include, but are not limited to, SHA-1, MD5, or othersimilar hash function.

The hash value within the formatted time-date information may becompared with the hash value generated by the remote machine 220. If thevalues do not match, it can be deduced that the property valueassociated with the time-date information was changed at remote device205. Accordingly, the time-date information is potentially unreliableand may therefore be discarded by remote machine 220. In such instance,because the time-date information is potentially unreliable, a userinterface can be provided to the user in order to resolve the conflict.Of course, other ways of resolving the conflict are also availablethrough standard practices well-known in the industry.

It should be noted that the above use of a hash or representation of aproperty value in order to determine when a change has occurred atremote device 205 is not limited to formatted time-date information. Forexample, comparison of property representations in order to determinewhen a property value has changed can be used without time-dateinformation. Such instances would be useful in determining whenproperties need to be synced down from remote device 205, without havingto compare values of the properties stored on remote machine 220.Accordingly, the use of the hash or remote property representationwithin the Sync URL or formatted time-date information is used forillustrative purposes only is not meant to limit or otherwise narrow thescope of the present invention, unless otherwise explicitly claimed.

FIG. 3 illustrates how time-date information may be formatted and storedat remote device 205. As shown in FIG. 3, item 355 has various fieldsfor a contact, which include property identifiers, property names and aninitial value for the properties. Of course, other items, properties,fields, etc. are also available, with the exception of a reservedtime-date property field. Accordingly, reference to item 355 contactinformation and the fields therein are used for illustrative purposesonly and are not meant to limit or otherwise narrow the scope of thepresent invention, except where explicitly claimed.

Also shown in FIG. 3, formatted time-date information can be stored inproperty field 375 as a field value 350. Example embodiments providethat the formatting may be in the form of Sync URL as shown in field350. An exploded view of parsed portions of field 350 are also shown inFIG. 3. The first portion of field 350 includes Sync URL 305. Thisportion identifies to devices that are scanning item 355 that thefollowing segments of the Sync URL include time-date information forvarious properties within item 355. It is noted, that the place holder315 normally reserved for locator information in the Sync URL 305 may ormay not be used.

Each of the following segments can be separated by an ampersand 340 andidentified through a property identification, e.g., property value 310.Also included within each segment of the Sync URL 305 in field 350 istime-date information associated with the property identification (e.g.,time_date_1 330 is associated with Prop ID_1). Example embodimentsprovide that a simple representation of the time-date information may beused in order to conserve valuable memory resources. For example, thetime-date information may be stored as a Hexadecimal number. To savefurther space, the time-date information can also be stored at a lowerresolution. For instance, time-date values are normally stored down to athousandth of a second. Example embodiments, however, provide forcreating the formatted time-date information or Sync URL with time-datevalues stored down to the second or to the minute. In addition, exampleembodiments provided that the time-date information can be stored in atime zone independent way. Accordingly, this will allow comparable timeswhen the nodes in the sync topology are in different time zones.

Also provided within each segment of the Sync URL 305 is a propertyrepresentation, e.g., property representation 320. Example embodimentsprovide that the property representation 320 may be in the form of ahash, which as previously described, can be used in determining if aproperty value has been changed since the property representation 320was generated. This indicates whether or not the time-date information330 is potentially unreliable.

With the exception of few fields, such as the notes field, the memoryavailable to store formatted time-date information is limited. As such,memory for storing time-date information for each and every property maynot be available or practical. Accordingly, the present inventionprovides for determining and choosing a limited set of property valuesfrom among the total number of property values within an item 355. Achoice of property values to include time-date information within theSync URL 305 of the present invention may be chosen based on variousconsiderations. For example, the choice may be based on those propertyvalues that were most recently changed. Alternatively, the propertyvalues chosen to have time-date information associated with them withinthe Sync URL 305 or formatted time-date information may be based onheuristical data such as the frequency of change for a particularproperty value. Of course, any other number of various ways for choosingproperty values to associate time-date information with is alsoprovided. Accordingly, the use of how the properties are chosen, e.g.,most recent changed properties, is used for illustrative purposes onlyand is not meant to limit or otherwise narrow the scope of the presentinvention unless otherwise explicitly claimed.

Because space is a consideration, and typically a subset of theproperties will need to be selected to have time-date informationassociated therewith, the present invention can also provide fordetermining if the other properties have changed since a lastsynchronization, as well as associates time-date information with them,within a reduced space. For example, the present invention provides forrepresenting the rest of the properties in a reduced format andassociating upper and/or lower bound time-date information for therepresentation. For instance, as shown in FIG. 3, appended to the end ofthe Sync URL 305 in field 350 is a segment with a property identifier360 holding a rest value. The property identifier 360 indicates todevices that are scanning the Sync URL 305 that the properties that donot have specific time-date information associated with them arepresented in this segment. Accordingly, a property representation 365 ofthe remaining property values can be used.

As with the other property representations previously described, e.g.property representation 320, property representation 365 for the rest ofthe property values may be in the form of a hash of all the remainingproperty values. As such, this property representation 365 may be usedin a similar way as those previously described property representationsto identify when one or more of the remaining property values haschanged since the last sync between a remote machine and a localmachine. Other example embodiments also provide time-date information370 can also be associated with the rest property to give an upperand/or lower boundary on when the remaining property values werechanged.

Although the rest segment was described as an additional segment of SyncURL, one would recognize that the rest segment may be formatted in itsown field. For example, where space or memory needs to be reserved, therest segment can be used to identify when one or more the propertieswithin an entire item 355 has changed. Accordingly, the use of the restsegment appended to the end of the Sync URL 305 is used for illustrativepurposes only and is not meant to limit or otherwise narrow the scope ofthe present invention except where explicitly claimed.

The present invention may also be described in terms of methodscomprising functional steps and/or non-functional acts. The following isa description of steps and acts that may be performed in practicing thepresent invention. Usually, functional steps describe the invention interms of results that are accomplished, whereas non-functional actsdescribe more specific actions for achieving a particular result.Although the functional steps and non-functional acts may be describedor claimed in any particular order, the present invention is notnecessarily limited to any particular order or combination of actsand/or steps. Further, the use of acts and/or steps in the recitation ofthe claims and in the following description of the flow chart for FIGS.4-8 are used to indicate the desired specific use of such terms.

FIG. 4-8 illustrates example flow charts for various exemplaryembodiments of the present invention. The following description of FIGS.4-8 will occasionally refer to corresponding elements from FIGS. 1B, 2and 3. Although reference may be made to a specific element from thesefigures, such elements are used for illustrative purposes only and arenot meant to limit or otherwise narrow the scope of the presentinvention unless otherwise explicitly claimed.

FIG. 4 illustrates an example flow chart of a method 400 of associatingtime-date information with a property value within a remote databasethat stores properties without a corresponding time-date field. Method400 includes an act of identifying 405 time-date information. Thetime-date information will correspond to one or more property values inthe remote database. Method 400 also includes an act of formatting 410the identified time-date information. The time-date information isformatted in a standard format parsable by one or more devices 210, 220within the distributed computing system 200. The standard formatting maybe a URI such as the Sync URL 305. The Sync URL 305 may be parsed intosegments separated by ampersand 340. Each segment may include a propertyidentifier 310, a representation of the property values 320 and arepresentation of the time-date information 330 corresponding to theproperty values. Example embodiments provide the representation for theproperty values 320 may be a hash of the particular property value.Further, the representation of the time-date information may be aHexadecimal number and/or can be stored down to the seconds or minutesand/or in a time zone independent format.

Method 400 also includes an act of sending 420 the formatted time-dateinformation. For example, the formatted time-date information may besent to the remote database for storage in a field 350 associated withthe remote property values. The field 350 may be, e.g., a notes field,hidden property, private expanded property, or any other similar unusedfield.

Other example embodiments provide that the property values that havetime-date information associated with them within the field 305 are asubset of the total number of property values. The subset may be chosenbased on values associated with the time-date information. For example,the most recent time-date information may be used to select the propertyvalues included within the subset. Alternatively, the frequency forwhich the property values have changed may be used to choose the subset.

In still other embodiments, the remaining portion of property valuesfrom the total number of property values may be combined in arepresentation value 365 and have time-date information associated withit 370. For example, the time-date information 370 may be a mostrecently changed value for a total number of properties within the restof the properties. Alternatively, it may also be bounded by a lowertime-date information 370 indicating when one of the properties withinthe remaining portion of property values was earliest in time to besynced. Further, the combined representation value 365 may be in theform of a hash of the remaining portion of property values.

FIG. 5 illustrates a method 500 of receiving and storing time-dateinformation with a property value in the database, wherein theproperties in a database are stored without corresponding time-datefield. Method 500 includes an act of receiving 505 formatted time-dateinformation. Time-date information being associated with property valuesand formatted in a standard format parsable by one or more devices 210,220 in the distributed computing system 200. Method 500 also includes anact of storing 510 the formatted time-date information. The time-dateinformation that is formatted may be stored in a database field 350associated with the property value such that the formatted time-dateinformation can be utilized to resolve data conflicts involving theproperty values.

Exemplary embodiments also allow for identifying and updating theformatted time-date information. For example, when a property value haschanged, the formatted time-date information may be identified as beingassociated with the property values. This formatted time-dateinformation can then be updated in the database field in accordance withthe changed property value. Example embodiments provide that this may bedone by the remote device 205 with the appropriate application software.For example, the formatted time-date information may be received andstored on the remote device 205, and a user of the remote device mayhave made the change. Alternatively, a local machine 210, 220 may havemade the change. The local machine 210, 220 storing unformattedtime-date information for properties associated with the one or moreproperty values in a database and stores this information withincorresponding time-date fields. In other words, the local machine 210,220 are high fidelity device.

FIG. 6 illustrates a method 600 of resolving a data conflict betweendevices in a distributed system. One of the devices within thedistributed computing system stores properties in a database without acorresponding time-date field. Method 600 includes an act of receiving605 a remote property value. The remote property value received for aremote property and corresponding remote time-date information is alsoreceived. Further, the remote time-date information is formatted in astandard format parsable by one or more devices in the distributedcomputing system, e.g., URI or Sync URL format. Method 600 also includesan act of detecting 610 a conflict. The conflict is between the remoteproperty value and a corresponding local property value.

Method 600 may also include a functional result-oriented step forutilizing 620 remote time-date information. The time-date informationmay be utilized to select an appropriate property value to synchronizebetween a local device and a remote device. A step 620 may include anact of parsing 622 remote time-date information. The remote time-dateinformation parsed according to a standard format to identify the remotetime and date, which indicates when the remote property value waschanged. Step 620 may also include an act of comparing 624 remote timeand date to local time and date. The local time and date indicating whena local property value was changed. Finally, step 620 may include an actof resolving 626 the conflict. The resolution of the conflict will bebased on the results of the comparison.

As previously mentioned, a standard format may be in the form of a URI.For example, the URI may be a URL parsed into segments. Segments mayinclude a property identification corresponding to the remote propertyvalue, a representation of the remote property value and arepresentation of the time-date information. Further, the representationof the remote property value may be a hash and the representation of thetime-date information may be a Hexadecimal number.

Other example embodiments provide for generating a local representationof the remote property from the remote property value. The localrepresentation may then be compared to the above-mentioned remoterepresentation for determining if the remote property value has changed.

FIG. 7 illustrates a method 700 for determining when a value for aproperty has changed since a last synchronization of the propertybetween the remote device and a local machine. Method 700 includes anact of receiving 705 a current value for a remote property. Further, aremote representation of a prior value of the remote property is alsoreceived. Method 700 may also include an act of generating 710 localrepresentation of remote property. The local representation beinggenerated from the current value for the remote property. Method 700also includes an act of comparing 715 the remote representation to thelocal representation. Finally, method 700 includes an act of determining720 prior remote property was changed. This determination indicates thatthe property value was changed after the remote representation wasgenerated. Accordingly, if time-date information is associated with theremote property in, e.g., Sync URL 305, such information is potentiallyunreliable, and it may be discarded.

FIG. 8 illustrates a method 800 of selecting a limited set of propertyvalues from among a plurality of property values. The property valuesare to be assigned time-date information for a device that storesproperties in a database without a corresponding time-date fields.Method 800 includes an act of receiving 805 property values from aremote device. Method 800 also includes an act of selecting 810 alimited set of time-date information. A limited set of property valuesmay be selected from the plurality of property values based on theavailable resources of the remote device. Method 800 also includes anact of identifying 815 a set of time-date information. Each of theproperty values in the limited set corresponding to a different portionof the set of time-date information. Method 800 also includes an act ofstoring 820 different portions of time-date information in a remotedatabase.

Method 800 may also include identifying the remaining portions ofproperty values and storing them as a representation value andassociating time-date information with them. For example, a portion oftime-date information for the remaining property values may beidentified (the remaining property values not being in the limited setof property values). The identified portion of time-date information maybe stored in one location in the remote database such that theidentified portion of time-date information corresponds to all of theremaining property values.

Embodiments within the scope of the present invention also includecomputer-readable media for carrying or having computer-executableinstructions or data structures stored thereon. Such computer-readablemedia can be any available media that can be accessed by a generalpurpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium which can be used to carryor store desired program code means in the form of computer-executableinstructions or data structures and which can be accessed by a generalpurpose or special purpose computer. When information is transferred orprovided over a network or another communications connection (eitherhardwired, wireless, or a combination of hardwired or wireless) to acomputer, the computer properly views the connection as acomputer-readable medium. Thus, any such connection is properly termed acomputer-readable medium. Combinations of the above should also beincluded within the scope of computer-readable media.Computer-executable instructions comprise, for example, instructions anddata which cause a general purpose computer, special purpose computer,or special purpose processing device to perform a certain function orgroup of functions.

FIG. 9 and the following discussion are intended to provide a brief,general description of a suitable computing environment in which theinvention may be implemented. Although not required, the invention willbe described in the general context of computer-executable instructions,such as program modules, being executed by computers in networkenvironments. Generally, program modules include routines, programs,objects, components, data structures, etc. that perform particular tasksor implement particular abstract data types. Computer-executableinstructions, associated data structures, and program modules representexamples of the program code means for executing steps of the methodsdisclosed herein. The particular sequence of such executableinstructions or associated data structures represents examples ofcorresponding acts for implementing the functions described in suchsteps.

Those skilled in the art will appreciate that the invention may bepracticed in network computing environments with many types of computersystem configurations, including personal computers, hand-held devices,multi-processor systems, microprocessor-based or programmable consumerelectronics, network PCs, minicomputers, mainframe computers, and thelike. The invention may also be practiced in distributed computingenvironments where tasks are performed by local and remote processingdevices that are linked (either by hardwired links, wireless links, orby a combination of hardwired or wireless links) through acommunications network. In a distributed computing environment, programmodules may be located in both local and remote memory storage devices.

With reference to FIG. 9, an exemplary system for implementing theinvention includes a general purpose computing device in the form of aconventional computer 920, including a processing unit 921, a systemmemory 922, and a system bus that couples various system componentsincluding the system memory 922 to the processing unit 921. The systembus 923 may be any of several types of bus structures including a memorybus or memory controller, a peripheral bus, and a local bus using any ofa variety of bus architectures. The system memory includes read onlymemory (ROM) 924 and random access memory (RAM) 925. A basicinput/output system (BIOS) 926, containing the basic routines that helptransfer information between elements within the computer 920, such asduring start-up, may be stored in ROM 924.

The computer 920 may also include a magnetic hard disk drive 927 forreading from and writing to a magnetic hard disk 939, a magnetic diskdrive 928 for reading from or writing to a removable magnetic disk 929,and an optical disk drive 930 for reading from or writing to removableoptical disk 931 such as a CD-ROM or other optical media. The magnetichard disk drive 927, magnetic disk drive 928, and optical disk drive 930are connected to the system bus 923 by a hard disk drive interface 932,a magnetic disk drive-interface 933, and an optical drive interface 934,respectively. The drives and their associated computer-readable mediaprovide nonvolatile storage of computer-executable instructions, datastructures, program modules and other data for the computer 920.Although the exemplary environment described herein employs a magnetichard disk 939, a removable magnetic disk 929 and a removable opticaldisk 931, other types of computer readable media for storing data can beused, including magnetic cassettes, flash memory cards, digitalversatile disks, Bernoulli cartridges, RAMs, ROMs, and the like.

Program code means comprising one or more program modules may be storedon the hard disk 939, magnetic disk 929, optical disk 931, ROM 924 orRAM 925, including an operating system 935, one or more applicationprograms 936, other program modules 937, and program data 938. A usermay enter commands and information into the computer 920 throughkeyboard 940, pointing device 942, or other input devices (not shown),such as a microphone, joy stick, game pad, satellite dish, scanner, orthe like. These and other input devices are often connected to theprocessing unit 921 through a serial port interface 946 coupled tosystem bus 923. Alternatively, the input devices may be connected byother interfaces, such as a parallel port, a game port or a universalserial bus (USB). A monitor 947 or another display device is alsoconnected to system bus 923 via an interface, such as video adapter 948.In addition to the monitor, personal computers typically include otherperipheral output devices (not shown), such as speakers and printers.

The computer 920 may operate in a networked environment using logicalconnections to one or more remote computers, such as remote computers949 a and 949 b. Remote computers 949 a and 949 b may each be anotherpersonal computer, a server, a router, a network PC, a peer device orother common network node, and typically include many or all of theelements described above relative to the computer 920, although onlymemory storage devices 950 a and 950 b and their associated applicationprograms 936 a and 936 b have been illustrated in FIG. 9. The logicalconnections depicted in FIG. 9 include a local area network (LAN) 951and a wide area network (WAN) 952 that are presented here by way ofexample and not limitation. Such networking environments are commonplacein office-wide or enterprise-wide computer networks, intranets and theInternet.

When used in a LAN networking environment, the computer 920 is connectedto the local network 951 through a network interface or adapter 953.When used in a WAN networking environment, the computer 920 may includea modem 954, a wireless link, or other means for establishingcommunications over the wide area network 952, such as the Internet. Themodem 954, which may be internal or external, is connected to the systembus 923 via the serial port interface 946. In a networked environment,program modules depicted relative to the computer 920, or portionsthereof, may be stored in the remote memory storage device. It will beappreciated that the network connections shown are exemplary and othermeans of establishing communications over wide area network 952 may beused.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. In a distributed computing system capable of synchronizing databetween distributed computing devices including work or home computersand mobile computing devices, a method of preserving memory resources atthe smaller mobile computing device which has limited physical resourcesfor storing data and thus is incapable of maintaining time-dateinformation for all properties of a data structure item that is to besynchronized with other local computing systems, the method comprisingacts of: receiving at a local computing device a plurality of propertyvalues from a remote device with limited physical resources for storingdata; selecting at the local computing device a limited set of propertyvalues from among the plurality of property values based on theavailable resources of the remote device; identifying at the localcomputing device a set of time-date information corresponding to thelimited set of property values selected; formatting at the localcomputing device the limited set of property values selected using astandard URI format that identifies the property and includes theidentified time-date information associated with each selected property;and receiving at the remote device the standard URI format for thelimited set of property values selected, and then storing the formattedtime-date information in one or more unused fields of a remote databaseof the remote device, the one or more unused fields comprising anyproperty field not reserved for storing time-date information in orderto take advantage of the unused fields to conserve memory resources atthe remote device.
 2. The method of claim 1, further comprising acts of:identifying a portion of time-date information from a plurality oftime-date information for one or more remaining property values notbeing in the limited set of property values, and the portion oftime-date information corresponding to when at least one of the one ormore remaining property values where modified by a user; and storing theidentified portion of time-date information in one location in theremote database such that the identified portion of time-dateinformation corresponds to all of the one or more remaining propertyvalues.
 3. The method of claim 2, wherein the one or more remainingproperty values are represented by a combined representation value. 4.The method of claim 3, wherein the combined representation value is ahash of the remaining portion of property values.
 5. The method of claim1, wherein each of the property values in the limited set are stored asa representation of the corresponding property value.
 6. The method ofclaim 5, wherein the representation of the corresponding property valuesare a hash of the corresponding property value.
 7. The method of claim1, wherein the available resources is a limited size of a field.
 8. Themethod of claim 1, wherein the selection of the limited set of propertyvalues is also based on historical information associated with themodification of the plurality of property values.
 9. The method of claim8, wherein the historical information is the frequency for which each ofthe plurality of property values are modified, and wherein the mostfrequently modified property values are selected.
 10. The method ofclaim 8, wherein the historical information is time-date information forthe plurality of property values, and wherein the most recently modifiedproperty values are selected.
 11. In a distributed computing systemcapable of synchronizing data between distributed computing devicesincluding work or home computers and mobile computing devices, acomputer program product for implementing a method of preserving memoryresources at a smaller computing device which has limited physicalresources for storing data and thus is incapable of maintainingtime-date information for all properties of a data structure item thatis to be synchronized with other local computing systems, the computerprogram product comprising a computer-readable storage medium containingcomputer executable instructions for implementing the method, andwherein the method is comprised of the acts receiving at a localcomputing device a plurality of property values from a remote devicewith limited physical resources for storing data; selecting at the localcomputing device a limited set of property values from among theplurality of property values based on the available resources of theremote device; identifying at the local computing device a set oftime-date information corresponding to the limited set of propertyvalues selected; formatting at the local computing device the limitedset of property values selected using a standard URI format thatidentifies the property and includes the identified time-dateinformation associated with each selected property; and receiving at theremote device the standard URI format for the limited set of propertyvalues selected, and then storing the formatted time-date information inone or more unused fields of a remote database of the remote device, theone or more unused fields comprising any property field not reserved forstoring time-date information in order to take advantage of the unusedfields to conserve memory resources at the remote device.
 12. Thecomputer program product of claim 11, further comprising computerexecutable instructions that can cause the distributed computing systemto perform the following: identify a portion of time-date informationfrom a plurality of time-date information for one or more remainingproperty values not being in the limited set of property values, and theportion of time-date information corresponding to when at least one ofthe one or more remaining property values where modified by a user; andstore the identified portion of time-date information in one location inthe remote database such that the identified portion of time-dateinformation corresponds to all of the one or more remaining propertyvalues.
 13. The computer program product of claim 12, wherein the one ormore remaining property values are represented by a combinedrepresentation value.
 14. The computer program product of claim 13,wherein the identified portion of time-date information for the one ormore remaining property values most recently time-date value, oldesttime-date value, or both.
 15. The computer program product of claim 13,wherein each of the property values in the limited set are stored as arepresentation of the corresponding property value.
 16. The computerprogram product of claim 15, wherein the representation of thecorresponding property values are a hash of the corresponding propertyvalue.
 17. The computer program product of claim 11, wherein each of theproperty values in the limited set are stored as a representation of thecorresponding property value.
 18. The computer program product of claim11, wherein the selection of the limited set of property values is alsobased on historical information associated with the modification of theplurality of property values.
 19. The computer program product of claim18, wherein the historical information is the frequency for which eachof the plurality of property values are modified, and wherein the mostfrequently modified property values are selected.
 20. The computerprogram product of claim 19, wherein the historical information istime-date information for the plurality of property values, and whereinthe most recently modified property values are selected.